1. Field of the Invention
The present invention relates to an input detection circuit, an input detection method, an input detection apparatus, and a computer readable medium that detect an input operation to a touch panel.
2. Description of the Related Art
Conventionally, there has been known a touch panel that can detect an input operation which touch the touch panel with a pen, a finger, or the like (see U.S. Pat. No. 6,469,267).
Especially, a resistive touch panel is composed of two transparent substrate electrodes that are separated by a space and opposed to each other, and a detection circuit that detects contact between the two transparent substrate electrodes. A voltage is applied to one of the two transparent substrate electrodes, so that when one of the two transparent substrate electrodes pressed by the finger comes in contact with another one of the two transparent substrate electrodes, a current is generated between the two transparent substrate electrodes. The touch panel detects the input operation to the touch panel by detecting the generated current. In addition, the touch panel detects an input position where the input operation has been executed, after the detection of the input operation.
In the touch panel described in U.S. Pat. No. 6,469,267, a voltage is always applied between the two transparent substrate electrodes, and hence surfaces of the two transparent substrate electrodes become a state like a capacitor (hereinafter simply referred to as “a capacitor state”). Therefore, when the two transparent substrate electrodes are pressed each other according to the input operation, an inrush current is temporarily generated, to thereby damage the surfaces of the two transparent substrate electrodes. Especially, when a specific part of the touch panel is operated many times, corresponding specific parts of the two transparent substrate electrodes are excessively damaged, and hence the conduction between the two transparent substrate electrodes is obstructed. As a result, it is impossible to detect the input operation.
In the touch panel, the two transparent substrate electrodes are composed of a transparent conductive polymer. Therefore, compared with an indium tin oxide (hereinafter referred to as “an ITO”) as a conventional transparent substrate membrane, it is easy for the transparent conductive polymer to receive damage by the inrush current. Especially, in the touch panel, a voltage equal to or less than 1V DC is applied between the two transparent substrate electrodes in order to extend the service life of the two transparent substrate electrodes. Thereby, it is easy for the touch panel to receive the influence of a noise, and the detection accuracy of the input operation does not improve.
Further, this kind of touch panel detects the input position after the detection of the input operation, the voltage equal to or less than 1V DC used for the detection of the input operation is generally used for the actuation of the touch panel. Similarly to this kind of touch panel, it is easy for the touch panel to receive the influence of a noise, and the input position is not detected with higher accuracy (i.e., a resolution is not improved). Especially, in this kind of touch panel, the detection accuracy of the input position reduces according to an increase in an area of the touch panel.
On the other hand, when a power supply circuit supplying a voltage used for the detection of the input operation, and another power supply circuit supplying a voltage used for the detection of the input position are added to this kind of touch panel, an increase in the cost of manufacture is caused by the increases in a power consumption and the number of parts though the detection accuracy of the input position improves certainly.